getting the X and Y coordinates for a div element

Question

I've been trying to make a javascript to get a X and Y coordinates of a div element. After some trying around I have come up with some numbers but I'm not sure how to validate the exact location of them(the script returns the X as 168 and Y as 258) I'm running the script with a screen resolution of 1280 x 800. This is the script I use to get this result:

function get_x(div) {
    var getY;
    var element = document.getElementById("" + div).offsetHeight;
    var get_center_screen = screen.width / 2;

    document.getElementById("span_x").innerHTML = element;
    return getX;
}

function get_y(div) {
    var getY;
    var element = document.getElementById("" + div).offsetWidth;
    var get_center_screen = screen.height / 2;

    document.getElementById("span_y").innerHTML = element;
    return getY;
}​

Now the question is. Would it be reasonable to assume that these are accurate coordinates returned by the function or is there an easy to to just spawn a little something on that location to see what exactly it is?

And finally how would I go about making this div element move? I know I should use a mousedown event handler and a while to keep moving the element but yeah any tips/hints are greatly appreciated my biggest concern is to how to get that while loop running.

Answer 1

By far, the easiest way to get the absolute screen position of an element is getBoundingClientRect.

var element = document.getElementById('some-id');
var position = element.getBoundingClientRect();
var x = position.left;
var y = position.top;
// Et voilà!

Keep in mind, though, that the coordinates don’t include the document scroll offset.